Step outside tonight and look at Jupiter shining brightly in the south. Now look to your right side and travel 235 trillion miles (378 trillion kilometers) out into the cosmos. Here, between the head of Pisces and the side of Aquarius, is a nondescript star called TRAPPIST-1, an ultracool red dwarf discovered in 1999.
trapeze artist-1 it was mostly forgotten until 2017, when NASA announced that it housed the most land-size planets found in the habitable zone of a single star to date. exoplanet-Hunters have been obsessed with TRAPPIST-1 ever since. At last count, the neighborhood had seven planets, nearly equaling the eight found in our own solar system. But is TRAPPIST-1 a mirror or a mirage? Could it contain Earth-like planets, and possibly life, or does its passing resemblance to the solar system hide alien planets with inhospitable conditions?
Cue the James Webb Space Telescope (Webb or JWST), which exoplanet astronomers hope will reveal the true nature of this unique planetary system. Using his ability to characterize the atmosphere of an exoplanetRecently tested on WASP-96b, JWST is observing each of the seven planets in its first year of operations, and we are on the cusp of early results.
Just 39 light-years from Earth, a close neighbor in cosmic terms, the star TRAPPIST-1 is not like the sun. The star is about one tenth the mass of the sun and about as wide as Jupiter. However, it’s what orbits it that excites exoplanet hunters. Three planets were discovered in 2016 by a Belgian telescope at the La Silla Observatory in Chile called TRAPPIST, the Small Telescope for Transiting Planets and Planetesimals.
That discovery was more than confirmed by the now retired NASA. Spitzer Space Telescope in 2017. “The Spitzer Space Telescope played a gigantic role in the discovery of the TRAPPIST-1 system and JWST is the follow-up,” Nikole K. Lewis, an exoplanet scientist at Cornell University, told Space.com.
Spitzer spent 1,000 hours looking at TRAPPIST-1 and was able to tell us that there were seven planets in the system. Spitzer also measured both the mass and radius of each world, allowing basic calculations of the densities of the planets, all of which are similar to Earth’s. Astronomers have been on tenterhooks ever since.
Examining their atmospheres
“We know that the TRAPPIST-1 planets are made of things like Earth,” Lewis said. “So they could have atmospheres similar to Earth’s.”
Lewis co-led a team that in 2018 used the hubble space telescope to scan the atmospheres of the planets. “We didn’t see any signs of atmospheres, but we know they don’t have the big, fluffy, hydrogen- and helium-rich atmospheres that you’d expect,” Lewis said. Such atmospheres are associated with giant gas planets like Saturn and Jupiter.
But Hubble had reached its limits. JWST entry. “The TRAPPIST system has long been in the JWST plan, and because we’ve known about it for six years, we were able to make sure we were looking at it to the best of JWST,” Lewis said.
TRAPPIST-1: a solar system 2.0?
And astronomers have spent that time learning as much as possible about the seven worlds of TRAPPIST-1. In 2018, a study suggested that its planets were rocky, and that some might be wetter than Earth. In 2021, another study argued that they were likely rocky, albeit less dense than the planets in our solar system.
The TRAPPIST-1 system probably doesn’t look much like the solar system. Although four of the seven planets occupy the star’s habitable zone, close enough to be warm enough to support liquid water, they all orbit its orbit. star more close than Mercury it’s sunny
Since the star is much dimmer than our sun, that may not affect temperatures too much, but it drastically affects conditions on the planets. For example, the closest planet, TRAPPIST-1b, orbits its star in 1.9 Earth days. That is a very short year. In TRAPPIST-1h, the furthest away, a year lasts just 19 days. Also, all the planets are likely tidally locked, just like the moon is with the Earth, so only one side receives daylight.
Despite these differences, TRAPPIST-1 remains the primary exoplanet target for JWST due to its diversity of rocky planets. And although it is one of the most studied planetary systems, scientists still believe that TRAPPIST-1 has many more secrets to reveal.
TRAPPIST-1 in transit
TRAPPIST-1 is the only star system we know of with seven potentially Earth-like planets, but it is far from the nearest planetary system. That honor goes to Proxima Centauri, 4.24 light-years from Earth.
So why the fascination with TRAPPIST-1, which is 10 times further away? “Proxima is not transiting and what we need are transiting exoplanets,” Lisa Kaltenegger, an astronomer at Cornell University, told Space.com. Our line of sight to the TRAPPIST-1 system is perfect, and our telescopes can see its seven planets crossing the star’s disk.
“The closest transiting planets give us the most circular signal, so TRAPPIST-1 is one of our favorite systems,” Kaltenegger said. Astronomers can watch the TRAPPIST-1 planets go round and round.
The first look at JWST
Can JWST figure out what’s in the atmospheres of these seven rocky exoplanets? Webb’s NIR Spec instrument makes it the only telescope capable of identifying the signatures of molecules such as methane, carbon dioxide and oxygen: possible signs of life on the surface and clues to the composition of a planet’s atmosphere. After some promising work deciphering the gases present in WASP-39b’s atmosphere, astronomers finally got a glimpse of JWST’s first glimpse of the TRAPPIST-1 system last week.
It has not yet been peer reviewed or published, but in a conference At the JWST headquarters, the Space Telescope Science Institute in Baltimore, on December 13, scientists discussed the telescope’s initial data from their observations of TRAPPIST-1g, the second-farthest planet from the star.
Björn Benneke, an astronomer at the University of Montreal in Canada, He showed that TRAPPIST-1g does not have a hydrogen-rich atmosphere. Olivia Lim, a Ph.D. student at the University of Montreal, also submitted a poster with similar results for TRAPPIST-1b (part of a reconnaissance Program of all TRAPPIST-1 planets), as did Alexander Rathcke, an astronomer at Harvard’s Smithsonian Center for Astrophysics, to observations from TRAPPIST-1c.
Thus, there are no headline-grabbing discoveries about any TRAPPIST-1 planet in the first JWST observations.
What’s next for JWST?
But don’t be discouraged by the lack of revelations in these early results. It’s all about reconnaissance – understanding how to best utilize the precision of JWST and its various instruments.
“Those first observations will get us to the same level we got to with Hubble, more or less, but we’ll know how to use the instruments we want to use,” Lewis said. “It will take multiple observations with JWST to build the signals we need, and with the longevity of JWST we can continue to review and learn more.”
Lewis will study TRAPPIST-1e. “He’s the one in the middle of the habitable zone that’s closest to the size of Earth,” he said.
Remember, this investigation is only about the atmospheres of the planets. “We can’t start asking about aliens probably for a few cycles!” Louis said.
But the science of exoplanets is not done in isolation. Lewis is working with the University of Montreal because their observations of TRAPPIST-1d and TRAPPIST-1f, two of the other planets in the habitable zone, together will make a fascinating cross-section.
“Having Venus, Earth and Mars in our own solar system has really told us a lot about why Earth is habitable, about global warming and what might happen if Earth were a little smaller,” Lewis said.
The Fundamental Future of TRAPPIST-1
One of the TRAPPIST-1 planets will go down in history for harboring the first detected atmosphere of an Earth-sized planet beyond our solar system. Over the coming months, years and decades, the TRAPPIST-1 system will gradually be revealed in exquisite detail. But in addition to discovering the true nature of its seven Earth-sized planets, expect to see the neighborhood used to conduct some fundamental exoplanet science.
“We will be able to examine the true influence of the star on a relatively Earth-like rocky planet,” Kaltenegger said, “and we will be able to see if our habitable zone concept really works in practice.”
All of this opportunity comes from the incredible features of a remarkably close star system. “The planets in TRAPPIST-1 are about the same size, but at different distances from their stars, so we can explore them and think about the processes that shape them,” Lewis said. “It’s like nature gave us this perfect lab experiment.”